J. Mater. Environ. Sci. 4 (2) (2013) 227-232
ISSN : 2028-2508
CODEN: JMESCN
Bhaskar et al.
Physical and Mechanical Properties of Coconut Shell Particle
Reinforced-Epoxy Composite
J. Bhaskar 1, V.K. Singh 2
1
Associate Professor, Department Of Mechanical Engineering Harcourt Butler Technological Institute,
Kanpur-208002 India
2
Associate Professor, Department Of Mechanical Engineering College of technology
G.B. Pant University of Agriculture& Technology, Pantnagar-263145, Uttrakhand, India
Received 14 July 2012, Revised 28 Oct 2012, Accepted 28 Oct 2012
* Corresponding author. E mail: [email protected]
Abstract
The natural fibre reinforced composites are being developed to save environment. Objective of investigation
was to evaluate the physical property-density and mechanical property-tensile properties. Coconut particle
reinforced composites were fabricated by reinforcing shell particle (size between 200-800μm) by wt% of 20,
25, 30 & 35 into epoxy matrix. Composites panels were made by casting method in open mould in very easy
way. Experimental results showed that density, ultimate strength, modulus of elasticity and % elongation
decreases with wt% of shell particle with in this range wt% 20-35 of reinforcement. Tensile strength of 25
MPa and modulus of elasticity of 654 MPa were retained even after of 35% reinforcement. Properties were
comparable for application only with compromising slightly with matrix property.
Keywords : Weight percentage-wt%, shell-S, particle, matrix, reinforcement, density, tensile strength.
1. Introduction
Composites consist of one or more discontinuous phases embedded in a continuous phase. The discontinuous
phase is usually harder and stronger than the continuous phase and is called the ‘reinforcement„ or
‘reinforcing material’, whereas the continuous phase is termed as the ‘matrix’. Properties of composites are
strongly dependent on the properties of their constituent materials, their distribution and the interaction among
them. The geometry of the reinforcement (shape, size and size distribution) influences the properties of the
composite to a great extent.
Natural fillers and fibers reinforced thermoplastic composite have successfully proven their high qualities
in various fields of technical application. As replacements for conventional synthetic fibers like aramid and
glass fibers are increasingly used for reinforcement in the thermoplastic due to their low density, good thermal
insulation and mechanical properties, reduced tool wear, unlimited availability, low price, and problem free
disposal. Wood fibre/particle provides a sufficient reinforcement at much lower cost than synthetic and
mineral filled thermoplastic. When synthetic and mineral fibres are used, machine wear and damage of
processing equipment is much higher than with wood filler. Fiber damage during processing is greatly
reduced when wood is utilized, which allows for recycling production waste with out compromising quality
[1].
Luo and Netravali [2], Ahmed [3], Faud [4] and Schneider [5] studied pineapple, filament wound cotton
fibre, oil palm wood flour and jute & kenaf fiber based composite respectively. Bhaskar J & V K Singh
investigated the compressive properties of coconut powder composites [6].
Coconut shell is one of the most important natural fillers produced in tropical countries like Malaysia,
Indonesia, Thailand, Sri Lanka and India. Many works have been devoted to use of other natural fillers in
composite in recent past and coconut shell filler is a potential candidate for the development of new
composites because of their high strength and modulus properties. The coconut particles also have remarkable
interest in the automatiove industry owing to its hard-wearing quality and high hardness (not fradile like glass
fiber), good acoustic resistance, moth-proof, not toxic, resistant to microbial and fungi degradation, and not
easily combustible.
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CODEN: JMESCN
Bhaskar et al.
Composite of high strength coconut filler can be used in broad range of applications as, building
materials, marine cordage, fishnets, furniture, and other household appliances. The objective of this paper is to
investigate the density and tensile properties of epoxy composite based coconut shell filler particles.
1.1. Particulate composite
As the name itself indicates, the reinforcement is of particle nature (platelets are also included in this
class). It may be spherical, cubic, tetragonal, a platelet, or of other regular or irregular shape, but it is
approximately equiaxed. In general, particles are not very effective in improving fracture resistance but they
enhance the stiffness of the composite to a limited extent. Particle fillers are widely used to improve the
properties of matrix materials such as to modify the thermal and electrical conductivities, improve
performance at elevated temperatures, reduce friction, increase wear and abrasion resistance, improve
machinability, increase surface hardness and reduce shrinkage. Particles are more commonly used as
extenders to lower the polymer use with other simultaneous improvement in properties.
2. Materials and methods
2.1. Coconut shell particle
Coconut shell particles are used as reinforcing material for investigation. Shell particles of size
between 200-800μm are prepared in grinding machine. Coconut shell filler are potential candidates for the
development of new composites because of their high strength and modulus properties. A approximate value
of coconut shell density is 1.60 g/cm3.
Figure 1: coconut shell
Figure 2: coconut shell particle
2.2. Epoxy Resin
Epoxy resin (ER) are one of the most important classes of thermosetting polymers which are widely
used as matrices for fiber-reinforced composite materials and as structural adhesives [1-6]. They are
amorphous, highly cross linked polymers and this structure results in these materials possessing various
desirable properties such as high tensile strength and modulus, uncomplicated processing, good thermal and
chemical resistance, and dimensional stability [1]. However, it leads to low toughness and poor crack
resistance, which should be upgraded before they can be considered many end-use applications [1,2].
In the present investigation epoxy resin SY-12(319) purchased from M/s RESINOVA CHEMIE
Limited, Kanpur India has been used as matrix material. The epoxy used is colourless, odorless and
completely nontoxic. Tensile, modulus of elasticity compressive, flexural, and impact strengths are 43 MPa,
800-820 kg/mm2, 90-100 MPa, 50-60 MPa, 2.5-4 kg-cm/cm2 respectively. Density is 1.15 g/cm3.
Brush Bond make epoxy resin SY-12(319) is a liquid solvent free epoxy resin. It has versatile
applications in technical and industrial applications. Curing takes place at room temperature and atmospheric
pressure after addition of hardener. Fully cured mixture has excellent mechanical, thermal properties and
atmospheric attack. The castings have good ageing characteristics.
2.3. Hardener
Hardener SY31(B) is a yellowish-green liquid. Hardener SY31(B) purchased from M/s RESINOVA
CHEMIE Limited, Kanpur, India has been used as curing agent. In the present investigation 8 % wt/wt has
been used in all material developed. Specific viscosity of hardener is 10-20 cps. The weight percentage of
hardener used in the present investigation is as per recommendation of Singh V.K. (2002) [7].
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Bhaskar et al.
2.4. Fabrication Methodology
The measured quantity of resin and coconut shell particle is mixed according to required 20wt% ,
25wt%, 30wt% and 35wt% is kept in the furnace at a temperature of 90 ± 10 °C for two hours as per the
recommendation of Singh V.K., 2002 [7]. The electric furnace (Temperature Range 0-6000C) used for this
purpose. At each interval of 30 minutes the solution have been taken out from the furnace and remixed by
mechanical stirrer at high speed. After two hours the whole solution is taken out and allowed to cool to a
temperature of 45°C. When a temperature of 45°C has been attained 8 wt% of the hardener is mixed
immediately. Due to addition of hardener high viscous solution has been obtained which is again mixed
mechanically by high speed mechanical stirrer. The viscous solution so obtained is poured in to different
moulds for sample preparation for tensile testing.
The viscous solution obtained from resin, hardener and filler materials is poured in to different moulds as
shown in figure No 3 for specimen preparation for tensile, compression, wear and impact testing. Flat plates as
required for tensile test. Tensile test specimens were prepared on milling machine as per ISO 527-2(1996).
Figure 3: Mould for plate casting
2.4. Density Calculation
Specimens of size 10x10x15 mm3 were taken from casted panel. Weights of these samples were measured
from weighing machine.
Density=mass/volume of sample
2.5 Tensile test
Tensile tests are used to determine the modulus of elasticity, elastic limit, elongation, proportional limit,
and reduction in area, tensile strength, yield point, yield strength and other tensile properties. In the present
investigation all the tensile tests are conducted as per ISO test procedure. The tests are conducted on 100 kN
servo hydraulic UTM machine under different strain rates under displacement mode of control.
The different displacement rates are taken as 0.01 mm/min, 0.1 mm/min, 1mm/min 10mm/min and
100mm/min. All tests are conducted at room temperature. The results in form of stress-strain diagrams are
presented in next chapter.
3. Results and discussion
3.1 Appearance
Appearance of coconut particle reinforced composite for various wt % are found to be opaque and dark
brown in color. Coconut particle can be seen in cross sectional view as well as in transverse view.
3.2. Density
Density is one of the most important mechanical properties of the particle board material. The density of
coconut shell particle reinforced composite for various wt % of particle are presented in Table No.1 and
figure No.4.
From table No.1 and & figure No.4 it is observed that density decreases w.r.t. wt% of shell particle. But
there is remarkable decrease of 0.14 g/cm3 in density when wt% of shell particle changes from 28% to 35%.
Here it is possible to comment that density decreases with increase of wt% of particle. The decrease in density
can be related to the fact that the coconut particles are light in weight but occupy substantial amount of space.
Particles are not closely bonded to each other due to open mould casting method.
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J. Mater. Environ. Sci. 4 (2) (2013) 227-232
ISSN : 2028-2508
CODEN: JMESCN
Bhaskar et al.
Table 1: Density of coconut shell particle reinforced composite
S. No.
Coconut particle
Coconut particle
Coconut particle
(20 wt %)
(25 wt %)
(30 wt %)
(gm/cm3)
(gm/cm3)
(gm/cm3)
1
1.293
1.287
1.285
2
1.287
1.283
1.280
3
1.285
1.278
1.277
Mean
1.288
1.283
1.280
Coconut particle
(35 wt %)
(gm/cm3)
1.170
1.171
1.173
1.171
Figure 4: Density variation with reinforcement wt% of coconut shell particle
In the present investigation density of Coconut particle filled composite are found be 1.288 gm/cm³ for 20wt
%, 1.283 gm/cm³ for 25wt%, 1.280 gm/cm³, for 30wt% and 1.171 gm/cm³ for 35wt%.
3.3. Tensile properties
The mechanical properties of the coconut particle filled epoxy resin composite materials were determined
by universal testing machine at 0.1mm/min strain rate under displacement control mode.
Table 2: Tensile Properties of coconut shell particle reinforced composite
S.No.
Ultimate strength (MPa)
Modulus of elasticity
(MPa)
% elongation
20 wt% Shell powder
reinforcement
30.60
25 wt% Shell
powder
reinforcement
29.40
30 wt% Shell
powder
reinforcement
28.80
35 wt%Shell
powder
reinforcement
25.20
856.00
756.00
684.00
654.00
25.44
25.436
25.06
21.00
Tensile property of 43 MPa and modulus of elasticity 8000 MPa of cured matrix was supplied by material
supplier. From table No. 2 it is clear that ultimate strength is maximum (28 MPa) for 20%wt of coconut shell
particle. It reduces with the increase of wt% of shell particle. From literature it has been noticed that tensile
properties increases with increase of particle size upto 0.250 mm size for 40%wt reinforcement [12 &13].
“Saupan” investigated that tensile properties (27-35 MPa) increases for coconut shell particle (50-200 μm)
reinforced into epoxy upto 0-15wt% and decrease beyond 15 wt%.
The reinforcement in this investigation is more than “Supan’s [12&13] investigations. Same fashion of
decrement in the tensile properties was also observed. Tensile strength of 25 MPa was retained even after
35%wt reinforcement of shell particle. But it was quite appreciable when compared with tensile strength
(24.8-19.8 MPa) and modulus of elasticity (633-318 MPa) respectively) of coir reinforced (5-15 wt%)
polyster composite.
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Ultimate strength (MPa)
J. Mater. Environ. Sci. 4 (2) (2013) 227-232
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Bhaskar et al.
31
30
29
28
27
26
25
18
20
22
24
26
28
30
32
34
36
coconut shell particle, wt%
Figure 5 (a): Variation of ultimate strength with %wt
of coconut shell particle
Figure 5 (b): Variation of modulus of elasticity with %wt
of coconut shell particle
Modulus of elasticity also decreases with the increase of particle wt% reinforcement. In same fashion, change
in modulus of elasticity % elongation was also decreasing with wt% of particle. Variation in ultimate
strength, modulus of elasticity and % elongation was also observed from figure No. 5 (a, b & c).
Figure 5 (c): Variation of % elongation with %wt of coconut shell particle
Figure 5 (d): Stress-Strain diagram for %wt of coconut shell particles.
It can be said that decreased tensile properties resulted from poor adhesion between the filler and
thermoplastic since no coupling or dispersing agents were used. From figure No 5(d) stress-strain diagram for
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J. Mater. Environ. Sci. 4 (2) (2013) 227-232
ISSN : 2028-2508
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Bhaskar et al.
number of various particle wt% composite, it is observed that samples of wt% between 20% to 35% shows
almost similar nature. But stress is maximum for 20%wt particle.
Stress-strain behavior of all four varieties of samples was observed linear at early stage of tensile test in
figure No. 5(d). In rest portion of stress-strain diagram, all samples showed similar nature. Only wt% of 35
samples failed very first among four types of samples. This is also indication of poor adhesion of particles or
direct contact of filler particles.
4. Conclusions
The Mechanical properties-tensile strength and modulus of elasticity was closely related to physical
property-density. Decreasing value of density would be because of poor adhesion, direct contact of shell
particles and void formation. This decrease of density resulted into decrease of tensile properties. Increase of
wt% of reinforcement requires pressurized fabrication technique or addition of any adhesion increasing
additive. Increase of proportion of particle size less than 200μm would be helpful to increase density as well
as tensile properties.
Acknowledgements
The authors express their gratitude and sincere thanks to Dr C L Gahlot, Asstt. Professor, Chemistry Deptt for
kind cooperation in experimentation and valuable guidance.
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